Tube-spinners, also referred to as self-rotating tube cleaning nozzle assemblies herein, are used in the water-blast industry to clean out heat-exchanger tubes, for example tubes in a hot water or steam boiler. Tubes-spinners are generally cylindrical in shape and two to four inches long, and range in size from about ½ inch to 1 inch in diameter. The size of tube-spinners are such that they fit inside heat exchanger tubes, with clearance between the body and tube for water and debris to flush out as the tube-spinner advances into the tube. FIG. 7 shows a general depiction of the tube cleaning process wherein pressurized water is delivered to a tube-spinner P1 via a hose H1 and lance L1 and controlled by a foot valve V1, and wherein the tube-spinner P1 is inserted into each individual tube T1 of a heat exchanger HX for cleaning.
An example prior art tube-spinner P1 is shown at FIG. 8 in the drawings. The particular example shown at FIG. 8 is a “15K Tube Spinner” manufactured by Jetstream of Houston, LLP (Houston, Tex.). As shown, the tube-spinner P1 includes a main body P100, a sleeve P200 that rotates around the main body P100, and a stationary nozzle P300 that is threaded onto the main body P100. The tube-spinner main body P100 is connected to a high pressure water source via a lance such the water flows in a direction D1 into an internal passage of the main body P100. A variety of nozzles P300 can be threaded onto the main body P100 with variously oriented and sized ports to discharge the water in spray jets, for example, spray jets S1 and S2. At the same time, the high pressure water causes the sleeve P200 to spin at very high speeds and one or more of the exiting radial jets S3 created by a hole P202 in the spinner's rotating sleeve impinges on the inside surface of the tube being cleaned. The combination of speed and pressure of the jets, along with length-wise movement of the nozzle along the tube, provide a cleaning action.
During the normal course of cleaning, there is opportunity between cleaning passes, as occurs when the tube-spinner P1 is being retracted from a tube so that it can be moved to the next one, that small particles, or sometimes viscous substances, fall into the gap G1 defined between the sleeve P200 and the body P100. These contaminants produce enough friction and/or drag that the torque produced by the jets in the sleeve cannot overcome it and the sleeve does not spin. When this happens, the process has to be stopped and the tube-spinners need to be disassembled, cleaned and reassembled.